1. Field of the Invention
The present invention relates to a washer pump apparatus, and more particularly to a washer pump apparatus in which a washer pump is fixed to a tank via a grommet.
2. Description of the Related Art
A washer pump for discharging a window washer liquid or a headlight washer liquid in a vehicle or the like comprises a motor portion and a pump portion which is driven by this motor portion. An inlet of the pump portion is connected to a washer tank via a grommet, and washer liquid in the washer tank is sucked in from the inlet due to the operation of the pump portion and is discharged from an outlet.
The motor portion of such a washer pump is generally structured by a rotor or a stator which is disposed at the internal portion of a cylindrical main body (a yoke housing). However, in a case in which the atmospheric temperature changes due to heat generated by the motor itself and the internal pressure of the motor portion changes, for example, in a case in which the internal pressure of the motor portion is in a state of negative pressure with respect to the atmospheric pressure, there is the possibility that water or dust may penetrate in through fine gaps or the like of the motor portion. Accordingly, there is a need to solve this drawback. In particular, in a washer pump for a vehicle or the like, although a sealing member is provided between the motor portion and the pump portion (i.e., pump room) and the motor portion is kept in an airtight state, when the interior of the motor portion is in a state of negative pressure, there is higher possibility that water may be sucked in from this sealed portion. Accordingly, it is essential to solve this drawback.
For this reason, conventionally, a so-called breathing hole which communicates the inside of the motor portion with the outside (the atmosphere) has been provided. Accordingly, even when heat is generated by the motor or the atmospheric temperature changes, the internal pressure of the motor portion is maintained the same as the atmospheric pressure (the relative difference in an air pressure between the inside and the outside of the motor portion 12A can be eliminated) so as to prevent water or dust from being sucked in.
For example, in a washer pump for a vehicle or the like such as that as described above, the washer pump often tends to be disposed at a position where there is a higher possibility that water will splash from the outside. Accordingly, when a simple breathing hole which communicates the motor portion with the outside is used, water enters in through this breathing hole, which is not preferable. For this reason, conventionally, there have been proposed structures in which it is difficult for water or the like to enter into the motor portion through a breathing hole. Examples of structures include a structure in which a breathing hole is formed in a labyrinthine shape (e.g., Japanese Utility Model Application Laid-Open (JP-U) No. 58-111400); a structure in which a waterproofing cover is provided at a breathing hole (opening) (e.g., Japanese Utility Model Application Laid-Open (JP-U) No. 5-50964); and a structure in which a breather pipe is connected to a breathing hole (opening) and one end of the pipe is located at a position where it is difficult for water or the like to splash (e.g., Japanese Utility Model Application Laid-Open (JP-U) No. 56-141550).
In the aforementioned structures in which the breathing hole is formed in a labyrinthine shape or a waterproofing cover or breather pipe is connected to the breathing hole, the interior of the motor portion can be left open to the atmosphere and the internal pressure of the motor portion can be made the same as the atmospheric pressure. Further, even if the motor portion is located at a position onto which it is easy for water or the like to splash, it is difficult for water or the like to enter into the motor portion through the breathing hole. As a result, it is possible to increase the degrees of freedom in selecting the position at which the motor portion is to be disposed.
With the aforementioned structures which are formed merely by breathing holes, the internal pressure of the motor portion can be made the same as the atmospheric pressure, and it is more difficult for water to enter in through the breathing hole. However, when the labyrinthine breathing hole is used, because the breathing hole is formed in a labyrinthine shape, the configurations of the component parts for forming the breathing hole are extremely complicated. For this reason, it becomes difficult to manufacture the washer pump apparatus, the manufacturing cost thereof is high, and the entire size of the apparatus is large. Further, in a case in which another component such as a waterproofing cover or a breather pipe is used, since another part such as the waterproofing cover or the breather pipe is newly needed, the number of component parts used thereby increases. Thus, in any of the above-described cases, there are drawbacks, and it has been desired to overcome these drawbacks.